Particulate composition

ABSTRACT

Nanoparticles are prepared from a colloidal system comprising a continuous phase and micelles, the micelles comprising surfactant material. A microemulsion is formed by admixing the colloidal system with a solution of an active material, such as a medicament, dissolved in a solvent wherein the solution forms a disperse phase with the micelles of surfactant material. At least the dispersed phase is quenched to a solid state and the continuous phase and solvent are removed to produce the nanoparticles. The nanoparticles can be incorporated in an aerosol composition suitable for deep lung delivery by means of a metered dose inhaler.

[0001] The present invention relates to a particulate composition and toa method for preparing a particulate composition. Particularly, but notexclusively, the present invention also relates to an aerosolcomposition including the present particulate composition and to the useof such an aerosol composition in administering a medicament, forexample, for treating a respiratory disease.

[0002] There have been a number of proposals to provide particulatecompositions comprising so-called nanoparticles. “Nanoparticles” areparticles whose average dimension lies within the range of from 1 nm toup to, but not including, 1000 nm.

[0003] EP-A-0526666 describes a process for preparing solid lipidmicrospheres having an average diameter lower than one micron. Theprocess comprises forming a microemulsion comprising a molten lipid,which may contain a drug, and a mixture of water and surfactant,dispersing the microemulsion in water at a temperature of between 2 and10° C., washing the lipid microspheres obtained with water throughdiafiltration to remove the surfactant and any free drug, andlyophilising.

[0004] WO 93/00076 describes nanoparticles as a carrier system fordrugs. The particles are formed from a biopolymer by desolvation,thermal denaturation, reaction with a coupling reagent and/or reactionwith a compound having two or more functional groups. The drug can beloaded into or onto the spherical particle, either simultaneously withthe preparation of the carrier system or sequentially, by the additionof a suspension of spherical particles to an appropriate drug solution.The preparation is said optionally to comprise the addition of 0.1 to 2%of a surfactant.

[0005] EP-A-0877033 describes a reverse micelle emulsion cross-linkedpolymerisation reaction to produce particles up to 100 nm. Thepolymerized reaction product is dried to remove solvent and the driedparticles dispersed in an aqueous buffer. Surfactant and other toxicmaterials are then separated from the particles.

[0006] WO 96/25919 describes an aerosol comprising droplets of anaqueous dispersion of nanoparticles. The nanoparticles comprisebeclomethazone particles having a surface modifier on the surfacethereof. The beclomethazone nanoparticles can be prepared by grinding ora micro-precipitation method.

[0007] EP-A-0274431 describes forming a mixture of one or moresurface-active agents, water and one or more physiologically activecompounds and emulsifying the mixture by means of a colloid mill and/ormicro fluidiser to produce a two phase coacervate composition.

[0008] It is an object of the present invention to provide a particulatecomposition in a dry state comprising nanoparticles which compositionprovides an improvement over the prior art.

[0009] It is a further object of the present invention to provide amethod for preparing a particulate composition.

[0010] It is a further object of the present invention to provide anaerosol composition comprising the particulate composition of thepresent invention and an aerosol liquid propellant.

[0011] According to a first aspect of the present invention there isprovided a particulate composition comprising particles, wherein thesaid particles:

[0012] (a) include an active material and, with respect to the totalweight of the particles, more than 2 wt % of a surfactant material;

[0013] (b) have an average diameter of more than about 1 nm and lessthan about 1000 nm;

[0014] (c) are spheroidal or spherical in shape; and

[0015] (d) contain no cross-linked polymer formed from a monomer orpreformed polymer with a cross-linking agent and initiator.

[0016] Preferably the active material is a medicament.

[0017] According to a further aspect of the present invention there isprovided an aerosol composition comprising a liquid aerosol propellantand the present particulate composition.

[0018] The aerosol composition can be in a form suitable for oralinhalation, nasal and/or ocular administration to a patient.

[0019] The surfactant material contained in the present particulatecomposition can determine the surface properties of the particles. Inparticular, the choice of surfactant material can permit the exteriorsurface of the particles to be tailored to a specific application.

[0020] For example, when contained in an aerosol composition thesurfactant material contained in the present particulate composition canaid dispersion of the particles throughout the liquid propellant.

[0021] The nanometer size or less of the present particles permitsdelivery in the form of an oral or nasal aerosol inhaler to the lowerpulmonary tissues, including the alveoli and lower airways.

[0022] The presence of the surfactant in the present particulatecomposition can ensure a smooth exterior surface to the particles.

[0023] The absence in the particles of the present particulatecomposition of cross-linked polymer formed using a cross-linking agentand initiator ensures the absence of any residual monomer, preformedpolymer, cross-linking agent or initiator. Any such residues areinevitably present in a cross-linked polymer product formed usingcross-linking agent and initiator, albeit, in small amounts, and arepotentially toxic in in vivo applications and capable of adverselyaffecting the stability of the medicament.

[0024] The present particles preferably comprise a core materialincluding the active material and a coating on the core materialcomprising the surfactant material.

[0025] Preferably the particulate composition comprises particles inwhich the core material is hydrophilic and is surrounded by surfactantcoating. Such particulate compositions having a hydrophilic core wouldbe particularly suitable for the production of peptide, nucleic acidand/or protein-containing particles. Some such systems may be suitablefor inhalation, particularly from metered dose inhalers.

[0026] Alternatively, however, the particulate composition can compriseparticles in which the core material is hydrophobic and is surrounded bysurfactant coating. Such an arrangement can provide a useful vehicle forthe oral delivery of lipophilic poorly soluble drugs, which can show lowabsorption due to their slow dissolution rate. Inclusion of such drugsin the present particulate composition with a lipophilic core can showan increased dissolution rate. Some such systems may be suitable forinhalation, particularly from metered dose inhalers.

[0027] Preferably the particles have an average diameter within therange of from about 1 nm up to less than about 1000 nm. More preferably,the particles have an average diameter within the range of from about 10nm to about 800 nm, even more preferably within the range of from about20 nm to about 400 nm.

[0028] For use in an aerosol composition intended for deep lung deliveryof a medicament, the present particulate composition ideally comprisesparticles having an average diameter within the range of from about 1 nmup to less than about 1000 nm.

[0029] Throughout the present specification, by the term “averagediameter” is meant the mean diameter calculated from photon spectroscopymeasurement.

[0030] Preferably the particles of the present particulate compositioncomprise, with respect to the total weight of the particles, up to about90 wt % surfactant material, more preferably up to about 80 wt %surfactant material, even more preferably up to about 60 wt % surfactantmaterial. The particles preferably comprise more than about 10 wt %,more preferably more than about 20 wt %, even more preferably more thanabout 30 wt % surfactant material, with respect to the total weight ofthe particles. The actual amount of surfactant material selected will bedependent on the particular benefits which it is desired to confer onthe resultant dry particles.

[0031] The surfactant material employed can be selected from the groupcomprising ionic (including anionic and cationic), nonionic,zwitterionic and amphoteric surfactants and mixtures thereof. Throughoutthe present specification the term “surfactant” includes within itsscope “emulsifier”. The surfactant may also include a co-surfactant.Suitably a surfactant for use in the present invention is selected fromthe group comprising phospholipids; sorbitan esters (some of which areknown as SPANs); poloxamers; polyoxyethylene sorbitan esters (some ofwhich are known as TWEENs); polyoxyethylene esters (some of which areknown as Brij); bile salts; sodium bis (2-ethylhexyl) sulphosuccinate(available commercially as Aerosol OT and known as AOT); and mixturesthereof. If desired, co-surfactant can be included for the surfactantselected.

[0032] A preferred surfactant for use in an aerosol composition islecithin in combination with propan-2-ol at a weight ratio of lecithinto propan-2-ol in the range of from 1:3 to 1:10, preferably at a weightratio of 1:3.

[0033] The present particulate composition can provide particles in adry state, by which is meant a particulate material that feels dry totouch and flows as a powder.

[0034] Where the active material present in the particulate compositionis a medicament it can be any medicament that can usefully be deliveredin the form of particles having a size of from about 1 nm up to about1000 nm.

[0035] Medicaments appropriate for delivery in the form of an aerosolcomposition intended for use as an inhaler include medicaments for usein the treatment and prevention of asthma and other conditionsassociated with reversible airways obstruction. Such medicaments eitheralone or in any combination can be selected from the group comprising:

[0036] (i) salbutamol, salbutamol sulphate, mixtures thereof andphysiologically acceptable salts and solvates thereof,

[0037] (ii) terbutaline, terbutaline sulphate, mixtures thereof andphysiologically acceptable salts and solvates thereof,

[0038] (iii) beclomethasone dipropionate and physiologically acceptablesolvates thereof,

[0039] (iv) budesonide and physiologically acceptable solvates thereof,

[0040] (v) triamcinolone acetonide and physiologically acceptablesolvates thereof,

[0041] (vi) ipratropium bromide and physiologically acceptable salts andsolvates thereof,

[0042] (vii) corticosteroid or bronchodilator, and

[0043] (viii) leukotriene antagonists.

[0044] Other examples of particulate medicaments suitable for oral ornasal inhalation by means of the present aerosol composition include:

[0045] (ix) peptides, proteins, nucleic acids and derivatives thereoffor use in the treatment and prevention of disease states; and

[0046] (x) insulin, calcitonin, growth hormone, lutenising hormonerelease hormone (LHRH), leuprolide, oxytocin and physiologicallyacceptable salts and solvates thereof for use in the treatment andprevention of disease states including diabetes.

[0047] Further examples of appropriate medicaments which can be formedinto the present particulate compositions may additionally be selectedfrom, for example, analgesics, e.g., codeine, dihydromorphine,ergotamine, fentanyl or morphine; anginal preparations, e.g., diltiazem;antiallergics, e.g., cromoglycate, ketotifen or nedocromil;anti-infectives e.g., cephalosporins, penicillins, streptomycin,sulphonamides, tetracyclines and pentamidine; antihistamines, e.g.,methapyrilene; antiinflammatories, e.g., beclomethasone dipropionate,fluticasone propionate, flunisolide, budesonide, rofleponide, mometasonefuroate or triamcinolone acetonide; antitussives, e.g., noscapine;bronchodilators, e.g., albuterol, salmeterol, ephedrine, adrenaline,fenoterol, formoterol, isoprenaline, metaproterenol, phenylephrine,phenyipropanolamine, pirbuterol, reproterol, rimiterol, terbutaline,isoetharine, tulobuterol, or(−)4-amino-3,5-dichlor-α[[[6-[2-(2-pyridinyl)ethoxy] hexyl]methyl]benzenemethanol; diuretics, e.g., amiloride; anticholinergics, e.g.,ipratropium, tiotropium, atropine or oxitropium; hormones, e.g.,cortisone, hydrocortisone or prednisolone; xanthines, e.g.,aminophylline, choline theophyllinate, lysine theophyllinate ortheophylline; therapeutic proteins and peptides, e.g., insulin orglucagon. It will be clear to a person skilled in the art that, whereappropriate, the medicaments may be used in the form of salts, (e.g., asalkali metal or amine salts or as acid addition salts) or as esters(e.g., lower alkyl esters) or as solvates (e.g., hydrates) to optimisethe activity and/or stability of the medicament.

[0048] Preferred medicaments are selected from salbutamol, salmeterol,fluticasone propionate and beclomethasone dipropionate and salts orsolvates thereof, e.g., the sulphate of albuterol and the xinafoate ofsalmeterol.

[0049] Medicaments can also be delivered in combinations. Preferredformulations containing combinations of active ingredients containsalbutamol (e.g., as the free base or the sulphate salt) or salmeterol(e.g., as the xinafoate salt) in combination with an anti-inflammatorysteroid such as a beclomethasone ester (e.g., the dipropionate) or afluticasone ester (e.g., the propionate).

[0050] Examples of nucleic acid systems include corrective plasmid DNA(pDNA) constructs capable of expressing a therapeutic gene. Preferrednucleic acid systems are pDNA constructs whose stability and activityhave been enhanced by pre-condensation with a polycationic peptide, forexample, a protamine such as protamine sulphate. Suitably any protamineis included at a concentration of 0.1 to 10 mg/mg, more suitably 0.8 to2 mg/mg, with respect to the nucleic acid.

[0051] The dosage requirements for any one medicament will be thoseconventionally employed in, for example, inhalers. For example, wherethe active material is salbutamol for use in relation to asthma theinhaler is employed as required, usually 1 or 2 actuations (i.e. puffs)between 0 and 4 times per day, with a single metered dose comprising 100micrograms of salbutamol in a volume of metered liquid propellantbetween 20 and 150 μl.

[0052] If desired, the particles of the present particulate compositioncan include material in addition to the active material and thesurfactant material. Such additional material can act as a matrix orcarrier. Preferably the weight ratio of the active material to anyadditional material present in the particles, other than the surfactantmaterial, lies within the range of from about 99:1 to about 1:99. Morepreferably such a ratio lies within the range from about 99:1 to about20:80

[0053] Suitably, such an additional material can be a polymericmaterial. Preferably such a polymeric material has a molecular weightwithin the range of from about 250 to about 10×10⁶ daltons. The presenceof a polymeric material in a particulate composition can permit, forexample, the sustained and controlled release of the active materialonce, for example, the particulate composition has been administered toa patient. Suitable examples of such polymeric materials includepolyacrylic acid; chitosan; polylactic-glycolic acid; polylactic acid;albumin; and hyaluronic acid. One or more than polymeric material can beincluded in order to give the desired properties.

[0054] Preferably the weight ratio of the active material such as amedicament to the total amount of polymeric material present lies withinthe range of from about 99:1 to about 1:99, more preferably within therange of from about 99:1 to about 20:80.

[0055] A further example of an additional material that can beneficiallybe included in the particles comprising the present particulatecomposition is a sugar. The sugar may be present with or without thepolymeric material.

[0056] Examples of suitable sugars include mono and/or disacharides,such as for example lactose, sucrose and trehalose. The inclusion of asugar in the present particles can confer stability on the activematerial during processing and storage of the particulate composition.Examples of active materials whose stability may be increased in thepresence of sugar include nucleic acid, peptide and/or protein baseddrugs. Sucrose is particularly preferred for use with nucleic acids.

[0057] The weight ratio of the active material such as a medicament toany sugar present in the particles preferably lies within the range offrom about 99:1 to about 1:99, more preferably from about 99:1 to about20:80.

[0058] Further examples of additional materials that can beneficially beincluded in the present particles, particularly when the active materialis a nucleic acid and the particulate composition is intended to be usedas an aerosol composition, include one or more cationic lipids as theymay facilitate cellular entry of genetic material and a peptide toprotect the nucleic acid. An example of a suitable cationic lipid is1,2-dioleoyl-3-trimethylammonium propane (DOTAP).

[0059] Any additional material present is suitably in the form of amatrix incorporating the active material.

[0060] The present particulate composition can thus providenanoparticles, as well as particles less than 1 nm in diameter,comprising an active material, such as a drug, as a major part of theparticle. Where the surfactant material is in the form of a coating, theactive material in the form of, for example, a medicament can comprise100 wt % of the core material.

[0061] In an aerosol composition according to the present invention, theliquid propellant can be selected from the group comprisinghydrocarbons, hydrochlorocarbons, chlorocarbons,hydrochlorofluorocarbons, hydrofluorocarbons, fluorocarbons and mixturesthereof. Hydrofluorocarbons and fluorocarbons are preferred havingregard to environmental considerations and local legislativerequirements. Preferred propellants for use in an aerosol compositionintended for administration to a patient include hydrofluoroalkanesselected from the group comprising 1,1,1,2-tetrafluoroethane,1,1,1,2,3,3,3-heptafluoropropane and mixtures thereof, optionally incombination with a minor proportion of n-alkane, for example n-hexane.

[0062] Suitably the aerosol composition comprises an aerosol liquidpropellant and the particulate composition at a weight ratio of liquidpropellant to particulate composition within the range of from about10,000:1 to about 25:1, more preferably within the range of from about1,000:1 to about 100:1. Additional ingredients can be included in theaerosol composition if desired.

[0063] Preferably the aerosol composition is supplied in the form of ametered dose inhaler.

[0064] According to a further aspect of the present invention there isprovided a metered dose inhaler containing the aerosol composition ofthe present invention.

[0065] The metered dose inhaler can be prepared by conventionalmanufacturing methods. For example, under the appropriate pressure theparticulate composition and the liquid propellant can be admixed inbulk, dosed into the container of an inhaler and sealed under a pressureof between about 689.476 Pa (10 psig) and about 8273.712 Pa (120 psig).Alternatively, the particulate composition, if desired dispersed in anorganic liquid at a preferred weight ratio of particles to organicliquid within the range of about 1:10 to about 1:100, and the liquidpropellant can be dosed separately to the container of an inhaler priorto sealing under pressure. The appropriate dosing and metering valvecan, in either instance, then be inserted.

[0066] According to a further aspect of the present invention theaerosol composition of the present invention is provided for use in theadministration of the deep lung delivery of a medicament to a patient inneed thereof.

[0067] Such a mode of administration can be employed to treatrespiratory disease, such as for example asthma, and/or to deliver amedicament to be absorbed systemically by the patient. Examples ofmedicaments beneficially delivered by deep lung systemic absorptioninclude medicaments containing a nucleic acid, a peptide and/or aprotein. Medicaments for deep lung delivery containing a peptide and/ora protein, such as for example insulin, are employed to treat, forexample, diabetes. Medicaments for deep lung delivery containing anucleic acid, such as for example pDNA constructs for expression ofcorrective proteins, immunostimulatory proteins and enzymes, ribonucleicacids and antisense oilgonucleotides, can be employed to treat, forexample, cystic fibrosis and cancer.

[0068] According to a further aspect of the present invention there isprovided the use of the present particulate composition in themanufacture of an aerosol composition for the lung delivery of amedicament for the treatment of, for example, respiratory disorders in apatient.

[0069] According to a further aspect of the present invention there isprovided a method of administering a particulate composition to apatient in need thereof comprising spraying the aerosol formed from theaerosol composition of the present invention on to or towards the areaintended to receive the particulate composition.

[0070] Where the aerosol composition is in a form intended for oral ornasal application, the method includes the patient inhaling theparticulate composition.

[0071] According to a further aspect of the present invention there isprovided a method for preparing a particulate composition comprisingparticles having an average diameter within the range of from about 1 nmup to less than about 1000 nm, wherein the method comprises:

[0072] (i) forming a colloidal system comprising a continuous phase andmicelles, the micelles comprising surfactant material;

[0073] (ii) forming a microemulsion by admixing the colloidal system ofstep (i) with a solution comprising an active material dissolved in asolvent, wherein the solution forms a disperse phase within the micellesof surfactant material;

[0074] (iii) quenching at least the disperse phase to a solid state; and

[0075] (iv) removing the continuous phase and the solvent so as to yieldthe said particles.

[0076] Preferably step (iii) includes snap freezing the continuous phaseand the disperse phase, suitably in liquid nitrogen. The continuousphase and the disperse phase can be removed by freeze-drying, otherwiseknown as lyophilising.

[0077] Alternatively, steps (iii) and (iv) can include quenching thedisperse phase to a temperature higher than the freezing point of thecontinuous phase, separating, for example by centrifugation orultrafiltration, the solidified disperse phase and the liquid continuousphase, and removing by freeze-drying the solvent from the dispersephase.

[0078] Preferably the continuous phase is an apolar liquid and thesolvent is water. Suitably the apolar liquid is a hydrocarbon,preferably selected from the group comprising iso-octane, octane,heptane, hexane, cyclohexane and mixtures thereof. The combination of anapolar solvent and an aqueous solution contained within reverse micelles(known as L₂ micelles) of surfactant material can yield particlescomprising a hydrophilic core material containing the active materialand a coating comprising the surfactant material.

[0079] Alternatively, the solvent can comprise a lipophiliccompound-solubilising liquid or a liquid miscible with a lipophiliccompound, and the continuous phase comprises a liquid immiscible withthe solvent, such as an aqueous based phase. The combination of anaqueous based continuous phase and a lipid containing disperse phasecontained within normal micelles (known as L₁ micelles) can yieldparticles comprising a hydrophobic core material containing the activematerial and a coating comprising the surfactant material.

[0080] The surfactant material is suitably selected from the groupcomprising anionic, cationic, nonionic, zwitterionic, amphotericsurfactants and mixtures thereof. As explained above, the surfactantmaterial can be an emulsifier and the surfactant material can include aco-surfactant. Suitable and preferred surfactants are those set outabove.

[0081] Preferably, the colloidal system formed in step (i) comprises aweight ratio of continuous phase to surfactant material within the rangeof from about 10,000:1 to about 30:70, preferably within the range offrom about 100:1 to about 40:60.

[0082] Preferably the solution of active material of step (ii) is at aconcentration of about 2,000 to about 0.1 μg/g, more preferably about2,000 to about 0.1 mg/g, active material in the solvent. The lowerlevels of concentration of the active material may be suitable for usewhen the active material is a nucleic acid.

[0083] Preferably the colloidal system of step (i) is admixed with thesolution of step (ii) at a weight of colloidal system to solution withinthe range of from about 45:55 to about 100:1, preferably within therange of from about 60:40 to about 95:5.

[0084] The solution of step (ii) can include dissolved materialadditional to the said active material. The additional material can beincluded in the solution at a concentration of from about 2000 to about0.1 mg/g, preferably at a concentration of from about 1500 to about 10mg/g, with respect to the solvent. As explained above, the additionalmaterial may be suitably selected from the group comprising non-crosslinked polymeric materials, sugars, other beneficial ingredients, suchas, for example, cationic lipids and peptides, and mixtures thereof.Where the active material includes a nucleic acid a polycationicpeptide, such as for example protamine sulphate may suitably be includedat a concentration of from about 0.1 to about 10 mg/mg, preferably 0.8to 2 mg/mg, with respect to the nucleic acid. The nucleic acid issuitably pre-condensed with the polycationic peptide. The cationic lipidis preferably 1,2-dioleoyl-3-trimethylammonium propane and can usefullybe included when the active material is a nucleic acid.

[0085] The active material can be a medicament. The medicament can beany of those mentioned above, the solvent being selected to dissolve themedicament chosen.

[0086] The present method can be employed to prepare the particulatecomposition of the present invention. The formation of the dispersephase within the micelles of the surfactant material ensures that thefinished particles have a spheroidal or spherical shape.

[0087] The particulate composition product of the present method can beemployed in the preparation of the present aerosol composition, in thepresent use in the manufacture of an aerosol composition for lungdelivery of a medicament for the treatment of, for example, arespiratory disorder in a patient, and in the present method ofadministering a particulate composition to a patient in need thereofcomprising spraying the aerosol formed from the present aerosolcomposition on to or towards the area intended to receive theparticulate composition.

[0088] If desired the particles formed by the present method can bewashed to reduce their content of surfactant material.

[0089] Embodiments of the present invention will now be described, byway of example only, with reference to the following examples and theaccompanying drawings, wherein:

[0090]FIG. 1 is a ternary phase diagram of an AOT/aqueous/iso-octanesystem at 20° C.;

[0091]FIG. 2 is a scanning electron micrograph of particles embodyingthe present invention;

[0092]FIG. 3 is a ternary phase diagram of a lecithin:propan-2-ol1:3/aqueous/iso-octane system at 20° C.;

[0093]FIG. 4 is a scanning electron micrograph of particles embodyingthe present invention;

[0094]FIG. 5 is a vertical cross section of a metered dose inhaler; and

[0095]FIG. 6 is a vertical cross section of the spring mechanism of themetered dose inhaler of FIG. 5.

GENERAL EXPERIMENTAL PROCEDURES

[0096] Construction of Ternary Phase Diagrams

[0097] Water-in-iso-octane microemulsions were produced by addingfiltered distilled water to a surfactant/iso-octane solution. Eachmixture was gently agitated with a bench vortex for several seconds andthen allowed to stand for 15 minutes to ensure equilibrium of themixture. Water addition was successively repeated to determine the phaseboundary between the crystal clear micellar phase and the opaquemultiphase phase of the system.

[0098] Following the above experimental procedure a ternary phasediagram was constructed for the ternary system of water/sodium bis(2-ethylhexyl) sulphosuccinate/iso-octane at 20° C. The phase diagram isshown in FIG. 1. AOT stands for Aerosol OT, which is the name for acommercially available sample of sodium bis (2-ethylhexyl)sulphosuccinate. Compositions to the right of the phase boundary lineshown in FIG. 1 are in the form of water-in-iso-octane microemulsions.

[0099] Following the above experimental procedure a ternary phasediagram was constructed for the ternary system ofwater/lecithin:propan-2-ol(1:3 by weight)/iso-octane. The phase diagramis shown in FIG. 3. Compositions to the right of the phase boundary lineshown in FIG. 3 are in the form of water-in-iso-octane microemulsions.

EXAMPLES

[0100] A drug, with or without a matrix, was dissolved in water. Theresulting solution was added to the selected surfactant/iso-octanecolloidal system to give a final aqueous phase comprising 1 to 30% byweight of the total emulsion composition.

[0101] The microemulsion drug-containing composition was snap frozen bysubmersion in liquid nitrogen.

[0102] The product was freeze-dried at −55° C. to remove the iso-octaneand the water.

[0103] Particle Size Analysis

[0104] Particles produced were dispersed in filtered iso-octane andsonicated for 3 minutes, transferred to a quartz cuvette and sealed toprevent iso-octane evaporation. The cuvette was inserted in a Coulter N4plus to measure the size of the particles. Multimodal analysis wasperformed using the Coulter N4 plus standard distribution processortechnology. Particle size analysis was repeated for n>7.

[0105] Scanning Electron Microscopy (SEM) of Nanoparticles

[0106] Excess surfactant was removed by washing the particles withiso-octane using centrifugation. The resulting nanoparticles were driedunder a nitrogen stream and splutter layered with gold. Scanningelectron micrographs of the resulting nanoparticles were taken using aPhilips XL 20 SEM.

[0107] BPLC Assay of Salbutamol Sulphate

[0108] Salbutamol sulphate concentrations were determined using reversephase BPLC (high pressure liquid chromatography). A C₁₈ column wasemployed at ambient temperature with detection at 278 nm. The mobilephase consisted of a methanol:water phase at a ratio of 55:45 v/v,containing heptane sulphonic acid 1.1013 g/l and adjusted to pH 3.0 withglacial acetic acid. The mobile phase was passed through the column at aflow rate of 1 mL/min.

[0109] Samples were prepared using a standard solution of 600 mL ofethanol made up to 1000 mL with water, and containing bamethane 7 μgmL⁻¹.

[0110] Metered Dose Inhaler

[0111] Aerosol compositions were dosed into the metered dose inhalerillustrated in FIGS. 5 and 6. The metered dose inhaler comprises aninverted container (1) and a metering valve (2). The inverted container(1) is capable of withstanding a pressure up to 6.895×10⁵ Pa (100 psig)and is closed by a closure cap (3). The metering valve (2) extendsthrough the closure cap (3) and includes a fixed volume chamber (4), aspring mechanism (5) biased to maintain the valve closed when not beingactuated and an outlet stem (6) which opens into an expansion chamber(7). The container (1) and metering valve (2) are mounted by support (8)in a holder (9) which is integral with an actuator tube (10) extendingat an obtuse angle away from the holder (9). As can be seen in thedrawing the expansion chamber (7) opens by way of a spray jet orifice(11) into the actuator tube (10). The container (1) contains the aerosolcomposition (12) comprising propellant and the particulate composition.

[0112] In use the container (1) is depressed relative to the holder (9)causing the chamber (4) to open to the atmosphere and the fixed volumeof liquefied gas therein to expand forcing the composition into theexpansion chamber (7) where the liquefied gas continues to expand andevaporate. The actuator tube (10) directs the aerosol.

Example 1

[0113] A microemulsion composition was prepared following the aboveprocedure from 78% w/w iso-octane, 6% w/w sodium bis (2-ethylhexyl)sulphosuccinate, and 16% w/w of an aqueous phase. The aqueous phasecomprised, with respect to the aqueous phase, 0.06% w/w bromothymol blueand 17.17% w/w polyacrylic acid (molecular weight 2000), with thebalance being water.

[0114] The size of the resulting particles was measured using the photoncorrelation spectroscopy technique described above employing the CoulterN4. The particles were found to be 232±58 nm, n=7 mean±sd.

[0115] The particles were also subjected to scanning electron microscopyemploying the procedure described above. FIG. 2 is the scanning electronmicrograph of the present particles. The particles appear spherical andto have a diameter of approximately 250 nm, which is in line with thedata from the photon correlation spectroscopy sizing data.

Example 2

[0116] Microemulsion compositions were prepared following the aboveprocedure for three compositions comprising iso-octane,lecithin:propan-2-ol(1:3 w/w) and an aqueous phase. The relativeproportions of each phase and the content of the aqueous phase are givenin Table I below. TABLE I Surfactant (% w/w) Iso-octane Lecithin:Aqueous Phase Formulation (% w/w) Propan-2-ol (1:3) (% w/w)/compositionB 25 45 30/salbutamol sulphate (17% w/v) C 35 45 20/salbutamol sulphate(17% w/v) D 40 40 20/salbutamol sulphate:lactose (70:30) (17% w/v)

[0117] The size of the resulting particles formed from each formulationwas measured by photon correlation spectroscopy employing the Coulter N4machine in the above described procedure. The results are given in TableII below. TABLE II Nanoparticle size by PCS (scattering intensity)Formulation (mean ± sd, n = 7) B Population 1 (50.4%): 216 ± 43 nmPopulation 2 (49.6%):  40 ± 15 nm C 34 ± 17 nm D 69 ± 39 nm

[0118] A scanning electron micrograph of the salbutamol sulphatenanoparticles resulting from Formulation B was measured using theprocedure described above. FIG. 4 is a representation of the resultingscanning electron micrograph. The particles shown in FIG. 4 appearspherical and generally less than 100 nm in size in keeping with themeasurements given in Table II.

Example 3

[0119] Each of the nanoparticles resulting from the ternary formulationsof Example 2 was employed to produce an aerosol composition.

[0120] In each case −30 mg of nanoparticles were dispersed in 0.5 gn-hexane with 3 minutes sonication in a plastic vial for use in apressurised metered dose inhaler. A Bespak BK 357 100 μL metering valvewas crimped in place and hydrofluoroalkane propellant (14 g HFA-227) wasadded using a pressure burette. The valve was actuated through amouthpiece with a 0.25 mm orifice.

[0121] Visual evaluation of the compositions was performed prior andsubsequent to sonication and at later time points to assess formulationstability and homogeneity.

[0122] The aerosol performance of each resulting nanoparticle HFAformulations was assessed by cascade impaction. The plates of anAndersen cascade impactor were coated with polyethylene glycol(molecular weight 300) to reduce particle bounce and re-entrainment.

[0123] In each case the pressurised metered dose inhaler was primed byfiring five shots to waste and then 20 actuations were introduced intothe Andersen cascade impactor, operating at 28.3 L min⁻¹, via a BPtwo-stage liquid impinger inlet. The actuator, inlet, impactor stagesand filter were washed with 10 mL solution of a 50% ethanol/50% watermixture by sonication in a polythene bag.

[0124] Each washing was assayed for salbutamol sulphate concentration byHLPC-UV according to the procedure described above.

[0125] The results in terms of fine particle fraction, mass medianaerodynamic diameter (MMAD) and geometric standard deviations (GSD) ofthe aerosols produced are given in Table III below. Three batches ofeach nanoparticle were employed to give the present results (mean±sd,n=5). TABLE III Fine Particle Fraction (ex device, Formulation <5.8 μm)(%) MMAD (μm) GSD (μm) B 58.3 ± 6.8 1.2 ± 0.4 2.3 ± 1.1 C 65.5 ± 5.1 1.3± 0.2 2.3 ± 0.3 D 59.0 ± 4.6 1.5 ± 0.6 1.9 ± 0.8 Model 88.0 ± 8   1.14 ±0.03 2.12 ± 0.05

[0126] Included in Table III are equivalent data for a model solutionsystem comprising a mixture of 30 mg hexyl biphenylacetate, 0.5 gn-hexane and 14 g HFA-227. The data with respect to nanoparticles of thepresent invention are comparable to that of the model system. The modelsystem represents the optimum that could be achieved with the presentapparatus.

[0127] The fine particle fraction is the fraction likely to get into thelungs. The fine particle fraction for each of formulation B, C and Dcompares well to that achieved using the model solution.

[0128] The MMAD is an indication of the potential deposition site in thelungs. For each of formulations B, C and D, as well as the model system,the relatively low MMAD recorded suggests deep lung deposition.

[0129] The GSD is an indication of the polydispersity of the aerosolsproduced.

[0130] The combination of high fine particle fraction and low MMADindicates very good performance of the aerosols. The present datasuggests that in use a high fraction of nanoparticles would be depositedwithin the lung with the deposition being mainly alveolar.

[0131] Each of formulations B, C and D comprising nanoparticles producedfrom the lecithin-based microemulsion and the HFA-227:hexane blendcould, on visual evaluation in the plastic vial of the metered doseinhaler, be seen to be in the form of a stable dispersion. Eachformulation appeared as a very fine homogeneous dispersion. The presenceof a dispersion suggests that some flocculation of the nanoparticleswithin the hexane/HFA blend had occurred. By contrast, the nanoparticleson dispersion in n-hexane alone produced an optically clear system.

[0132] No sedimentation or creaming of the flocculation in theEFA-227/n-hexane blend was observed over several months. The absence ofsedimentation and creaming suggests that the flocculated particles musthave been less than 1 μm in size, and is desirable in order to ensurereproducible dosing.

[0133] The flocculation in the HFA-227/hexane system was removed onaerosolisation, as can be seen from the results recorded in Table IIIfor formulations B, C and D, relative to the model system.

[0134] By comparison, it proved impossible to disperse the product ofExample 1 above in an HFA propellant. Even with the inclusion of aco-solvent for the AOT/iso-octane at a level of up to 10% w/w thenanoparticles aggregated and adsorbed on the wall of the pressurisedmetered dose inhaler vial.

Example 4

[0135] Nanoparticles were formed using the lecithin:propanol-2-ol 1:3 byweight surfactant system of Example 2 including as the active materialpEGFP-N1 reporter plasmid DNA (4700 base pairs). The particles alsocontained protamine sulphate (1:1 by weight with respect to pDNA) andsucrose at a concentration of 0.5M in the aqueous phase.

[0136] Nanoparticle formation was confirmed by photon correlationspectroscopy.

1. Particulate composition comprising particles wherein the saidparticles: (a) include a medicament and, with respect to the totalweight of the particles, more than 2 wt % of a surfactant material; (b)have an average diameter of more than about 1 nm and less than about1000 nm; (c) are spheroidal or spherical in shape; and (d) contain nocross-linked polymer formed from a monomer or preformed polymer with across-linking agent and initiator.
 2. Particulate composition accordingto claim 1 wherein the particles comprise a core material including themedicament and a coating on the core material comprising the surfactantmaterial.
 3. Particulate composition according to claim 2 wherein thecore material is hydrophilic.
 4. Particulate composition according toclaim 2 wherein the core material is hydrophobic.
 5. Particulatecomposition according to any one of the preceding claims wherein theparticles have an average diameter of more than about 1 nm, preferablywithin the range of from about 10 nm to about 800 nm, even morepreferably within the range of from about 20 nm to about 400 nm. 6.Particulate composition according to any one of the preceding claimswherein the particles comprise, with respect to the total weight of thesaid particles, up to about 90 wt % surfactant material, preferably upto about 60 wt % surfactant material.
 7. Particulate compositionaccording to any one of the preceding claims wherein the surfactant isselected from the group comprising emulsifiers, ionic, nonionic,zwitterionic, amphoteric surfactants and mixtures thereof. 8.Particulate composition according to any one of the preceding claimswherein the surfactant material is selected from the group comprisingphospholipids, sorbitan esters, poloxamers, polyoxyethylene sorbitanesters, polyoxyethylene esters, bile salts, sodium bis (2 ethylhexyl)sulphosuccinate and mixtures thereof.
 9. Particulate compositionaccording to any one of the preceding claims wherein the medicament isselected from the group comprising salbutamol, salbutamol sulphate,terbutaline, terbutaline sulphate, ipratropium bromide or anyphysiologically acceptable salts or solvates thereof; beclomethasonedipropionate, budesonide, triamcinolone acetonide or any physiologicallyacceptable solvates thereof; corticosteroid, bronchodilator; peptides,proteins, nucleic acids or derivatives thereof; insulin, calcitonin,growth hormone, lutenising hormone releasing hormone, leuprolide,oxytocin or any physiologically acceptable salts or solvates thereof; orany mixture thereof.
 10. Particulate composition according to any one ofthe preceding claims wherein the particles further comprise a polymericmaterial, preferably having a molecular weight between 250 and 10×10⁶daltons.
 11. Particulate composition according to claim 10 wherein theweight ratio of medicament to polymeric material lies within the rangeof from about 99:1 to about 1:99.
 12. Particulate composition accordingto any one of the preceding claims wherein the particles furthercomprise a sugar, preferably a mono and/or a disaccharide. 13.Particulate composition according to claim 12 wherein the weight ratioof active material to sugar lies within the range of from about 99:1 toabout 1:99.
 14. Particulate composition according to any one of thepreceding claims wherein the particles further comprise a cationiclipid, preferably 1,2-dioleoyl-3-trimethylammonium propane. 15.Particulate composition according to any one of the preceding claimswherein the particles include nucleic acid precondensed withpolycationic peptide, preferably protamine sulphate.
 16. A method forpreparing a particulate composition comprising particles having anaverage diameter within the range of from about 1 nm to less than about1000 nm, wherein the method comprises: (i) forming a colloidal systemcomprising a continuous phase and micelles, the micelles comprisingsurfactant material; (ii) forming a microemulsion by admixing thecolloidal system of step (i) with a solution of a medicament dissolvedin a solvent, wherein the solution forms a disperse phase within themicelles of surfactant material; (iii) quenching at least the dispersephase to a solid state; and (iv) removing the continuous phase and thesolvent so as to yield the said particles.
 17. A method according toclaim 16 wherein step (iii) includes snap freezing the continuous phaseand the disperse phase.
 18. A method according to claim 17 wherein thesnap freezing occurs in liquid nitrogen.
 19. A method according to claim17 or claim 18 wherein the continuous phase and the solvent are removedby freeze-drying.
 20. A method according to claim 16 wherein steps (iii)and (iv) include quenching the disperse phase to a temperature higherthan the freezing point of the continuous phase, separating thesolidified disperse phase and the continuous phase, and removing byfreeze drying the solvent from the disperse phase.
 21. A methodaccording to claim 20 wherein the solidified disperse phase is separatedfrom the continuous phase by centrifugation or ultrafiltration.
 22. Amethod according to any one of claims 16 to 21 wherein the continuousphase is an apolar liquid and the solvent is water.
 23. A methodaccording to claim 22 wherein the apolar liquid is a hydrocarbon.
 24. Amethod according to claim 23 wherein the hydrocarbon is selected fromthe group comprising iso-octane, octane, heptane, hexane, cyclohexane,benzene and mixtures thereof.
 25. A method according to any one ofclaims 16 to 21 wherein the solvent comprises a lipophiliccompound-solubilising liquid or a liquid miscible with a lipophiliccompound, and the continuous phase comprises a liquid immiscible withthe solvent, preferably the continuous phase is aqueous based.
 26. Amethod according to any one of claims 16 to 25 wherein the surfactantmaterial is selected from the group comprising emulsifiers, anionic,cationic, nonionic, zwitterionic, amphoteric surfactants and mixturesthereof.
 27. A method according to claim 26 wherein the surfactantmaterial is selected from the group comprising phospholipids, sorbitanesters, poloxamers, polyoxyethylene sorbitan esters, polyoxyethyleneesters, sodium bis (2-ethylhexyl) sulphosuccinate, bile salts andmixtures thereof.
 28. A method according to any one of claims 16 to 27wherein the colloidal system formed in step (i) comprises a weight ratioof continuous phase to surfactant material within the range of fromabout 10,000:1 to about 30:70, preferably within the range of from about100:1 to about 40:60.
 29. A method according to any one of claims 16 to28 wherein the solution of medicament of step (ii) is at a concentrationof about 2,000 to about 0.1 μg/g medicament in the solvent.
 30. A methodaccording to any one of claims 16 to 29 wherein the colloidal system ofstep (i) is admixed with the solution of step (ii) at a weight ratio ofcolloidal system to solution within the range of from about 45:55 toabout 100:1, preferably within the range of from about 60:40 to about95:5.
 31. A method according to any one of claims 16 to 30 wherein thesolution of step (ii) includes dissolved material additional to the saidmedicament.
 32. A method according to claim 31 wherein the additionaldissolved material is selected from the group comprising polymericmaterials, sugars, cationic lipids, peptides and mixtures thereof.
 33. Amethod according to claim 31 or claim 32 wherein the additional materialis contained in the solution at a concentration of about 2,000 to about0.1 mg/g, preferably at a concentration of about 1,500 to about 10 mg/g,with respect to the solvent.
 34. A method according to any one of claims16 to 33 wherein the medicament is selected from the group comprisingsalbutamol, salbutamol sulphate, terbutaline, terbutaline sulphate,ipratropium bromide or any physiologically acceptable salts or solvatesthereof; beclomethasone diproprionate, budesonide, triamcinoloneacetonide or any physiologically acceptable solvates thereof;corticosteroid, bronchodilator; peptides, proteins, nucleic acids orderivatives thereof; insulin, calcitonin, growth hormone, lutenisinghormone releasing hormone, leuprolide, oxytocin or any physiologicallyacceptable salts or solvates thereof; or any mixture thereof.
 35. Amethod according to any one of claims 16 to 34 for preparing theparticulate composition according to claim
 1. 36. An aerosol compositioncomprising a particulate composition according to any one of claims 1 to15 or as prepared by the method according to any one of claims 16 to 35,and a liquid aerosol propellant.
 37. An aerosol composition according toclaim 36 wherein the liquid propellant is selected from the groupcomprising hydrocarbons, hydrochlorocarbons, chlorocarbons,hydrochlorofluorocarbons, chlorofluorocarbons, hydrofluorocarbons,fluorocarbons and mixtures thereof.
 38. An aerosol composition accordingto claim 37 wherein the liquid propellant is a hydrofluoroalkaneselected from the group comprising 1,1,1,2-tetrafluoroethane,1,1,1,2,3,3,3-heptafluoropropane and mixtures thereof.
 39. An aerosolcomposition according to any one of claims 36 to 38 wherein the aerosolcomposition has a weight ratio of propellant to particulate compositionwithin the range of from about 10,000:1 to about 25:1, preferably fromabout 1,000:1 to about 100:1.
 40. An aerosol composition according toany one of claims 36 to 39 provided in the form of a metered doseinhaler.
 41. An aerosol composition according to any one of claims 36 to40 in a form suitable for oral inhalation, nasal and/or ocularadministration.
 42. An aerosol composition according to any one ofclaims 36 to 41 for use in the administration to the lung of amedicament to a patient in need thereof.
 43. An aerosol compositionaccording to claim 42 for use in the treatment of respiratory disease.44. An aerosol composition according to claim 42 or claim 43 wherein themedicament, for example a nucleic acid, a peptide and/or a protein, isintended to be absorbed systemically by the patient.
 45. A metered doseinhaler containing an aerosol composition according to any one of claims36 to
 44. 46. Use of the particulate composition according to any one ofclaims 1 to 15 or of the product of any one of claims 16 to 35 in themanufacture of an aerosol composition for lung delivery of a medicamentfor the treatment of, for example, a respiratory disorder in a patient.47. A method of administering a particulate composition to a patient inneed thereof comprising spraying the aerosol formed from the aerosolcomposition according to any one of claims 36 to 44 on to or towards thearea intended to receive the particulate composition.
 48. A methodaccording to claim 47 wherein the patient inhales the aerosol.